Modern science and research have shown that old-school methods of preserving food in the UK are not always sufficient to ensure safe storage and consumption in the months to come. Polytunnel gardeners who are interested to looking for methods (other than freezing) to preserve the produce that they grow in their undercover growing area would do well to look into the US practice of home canning – especially pressure canning, which can allow for the safe preservation and storage of low-acid foods.
What is Pressure Canning?
Pressure canning is a method of preservation that uses a pressure canner to superheat steam to get the internal temperatures of the jar contents much higher than can be achieved with any amount of direct heating of their contents. This is the only sure way to eradicate botulinum toxins from the contents of your jars and the only safe way to preserve certain foodstuffs for a long shelf-life in sealed jars.
What Can I Preserve Using Pressure Canning?
Pressure canning can be used to preserve a wide range of polytunnel produce, and products made from the things you have grown. You can preserve jars of low-acid vegetables, soups, stews, pastas sauces and more, without needing to add salt, sugar, or vinegars.
The amount of pressure and temperatures required for different foods are different, so it is important to get a good reference book on pressure preserving and to use this carefully in order to make sure that you are safely preserving your polytunnel produce.
What Do I Need For Pressure Canning?
It is an annoying fact that we in a UK lag far behind our American cousins when it comes to safe and sustainable canning techniques that do not involve the use of large amounts of sugar or vinegar. For this reason, it can sometimes be difficult to get your hands on the equipment you need to make a start on home pressure canning in the UK. That said, while it can be more expensive than it would be in the States, it is possible for UK polytunnel gardeners and home preservers to get their hands on the things that they need.
To start pressure canning you will need:
- A pressure canner. (These can be ordered online, though will usually have to be shipped over the pond).
- Suitable preserving jars intended for home pressure canning. (Ideally with two-part lids.)
- A good instruction book with recipes for pressure canning.
Foods that have been properly pressure canned will last almost indefinitely as long as the seal is not broken, so can be stored without the need for freezing or the use of further energy/ fuels. Have you tried pressure canning in the UK? Let us know how you have fared in the comments below.
Elizabeth Waddington is a writer and green living consultant living in Scotland. Permaculture and sustainability are at the heart of everything she does, from designing gardens and farms around the world, to inspiring and facilitating positive change for small companies and individuals.
She also works on her own property, where she grows fruit and vegetables, keeps chickens and is working on the eco-renovation of an old stone barn.